Counting Problems( Week 8 Practice) 1. There are 10 triangles. Each triangle has exact one shared side with another triangle. How many sides are there in total? 3. A 12-hour chime clock strikes 1 chime at one o'clock, 2 chimes at two o'clock, 3 chimes at three o'clock,..., and 12 chimes at 12 o'clock. What is the maximum total number of chimes the clock will strike in a hours period? 4. When the order of the digits of 151 is reversed, the number remains the same. How many counting numbers between 200 and 900 remain the same when the order of their digits is reversed? 5. When a natural number is multiplied by itself, the result is a square number. Such as 1, 4, 9, 16, and 25. How many square numbers are there between 9000 and 10000 inclusively? |